Last night I discovered that Wyrd Sisters, Terry Pratchett's book about Discworld witches, was broadcast by Radio 4 as a play a few weeks ago. Luckily, it is still available to listen to and I'm really enjoying it.
The link to find it is here: http://www.bbc.co.uk/programmes/b007jl80
The tale, which starts with the King of Lancre being murdered in a bid for the throne as three witches meet on a blasted heath, is dramatised in four parts by Vince Foxall. It stars Sheila Hancock as Granny Weatherwax, Lynda Baron as Nanny Ogg and Deborah Berlin as Magrat Garlick. The radio play was apparently first broadcast on BBC Radio 4 in 1995, but I missed it then. I'm pleased to be catching up with it now.
You can view the book Wyrd Sisters (pictured above) on Amazon and you can also read my review of Terry Pratchett The Witches Boardgame here: http://www.badwitch.co.uk/2014/01/review-terry-pratchett-witches-boardgame.html